This is a social network that was leaked. I would be somewhat surprised if the same attack didn't also get quite a few of someone's "friend network" on Faceboo

This is a social network that was leaked. I would be somewhat surprised if the same attack didn't also get quite a few of someone's "friend network" on Facebook and the like. Certainly was more likely in the past, but with some of the modern botnets, I have little faith some of my elderly family haven't been hacked in this way. To that end, I'm curious on how they could have protected this better? Almost certainly doable, but I don't know of many ways you can protect people that are on my contact list from getting leaked if my contact list is leaked. Which is essentially what this is.